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We report a geophysical study across an active normal fault in the Southern Apennines. The surveyed area is the “Il Lago” Plain (Pettoranello del Molise), at the foot of Mt. Patalecchia (Molise Apennines, Southern Italy), a small tectonic basin filled by Holocene deposits located at the NW termination of the major Quaternary Bojano basin structure. This basin, on the NE flank of the Matese Massif, was the epicentral area of the very strong 26 July, 1805, Sant’Anna earthquake (I0 = X MCS, Mw = 6.7). The “Il Lago” Plain is bordered by a portion of the right-stepping normal fault system bounding the whole Bojano Quaternary basin (28 km long). The seismic source responsible for the 1805 earthquake is regarded as one of the most hazardous structures of the Apennines; however, the position of its NW boundary of this seismic source is debated. Geological, geomorphological and macroseismic data show that some coseismic surface faulting also occurred in correspondence with the border fault of the “Il Lago” Plain. The study of the “Il Lago” Plain subsurface might help to constrain the NW segment boundary of the 1805 seismogenic source, suggesting that it is possibly a capable fault, source for moderate (Mw < 5.5) to strong earthquakes (Mw ≥ 5.5). Therefore, we constrained the geometry of the fault beneath the plain using low-frequency Ground Penetrating Radar (GPR) data supported by seismic tomography. Seismic tomography yielded preliminary information on the subsurface structures and the dielectric permittivity of the subsoil. A set of GPR parallel profiles allowed a quick and high-resolution characterization of the lateral extension of the fault, and of its geometry at depth. The result of our study demonstrates the optimal potential of combined seismic and deep GPR surveys for investigating the geometry of buried active normal faults. Moreover, our study could be used for identifying suitable sites for paleoseismic analyses, where record of earthquake surface faulting might be preserved in Holocene lacustrine sedimentary deposits. The present case demonstrates the possibility to detect with high accuracy the complexity of a fault-zone within a basin, inferred by GPR data, not only in its shallower part, but also down to about 100 m depth.

The city of Naples (Campanian region, Southern Italy) has been hit by the strongest earthquakes located inside the seismogenic areas of the Southern Apennines, as well as by the volcano-tectonic earthquakes of the surrounding areas of the Campi Flegrei, Ischia and Vesuvius volcanic districts. An analysis of the available seismic catalogues shows that in the last millennium, more than 100 earthquakes have struck Naples with intensities rating I to III on the Mercalli&ndash, Cancani&ndash, Sieberg (MCS) scale over the felt level. Ten of these events have exceeded the damage level, with a few of these possessing an intensity greater than VII MCS. The catastrophic earthquakes of 1456 (I0 = XI MCS), 1688 (I0 = XI MCS) and 1805 (I0 = X MCS) occurred in the Campania&ndash, Molise Apennines chain, produced devastating effects on the urban heritage of the city of Naples, reaching levels of damage equal to VIII MCS. In the 20th century, the city of Naples was hit by three strong earthquakes in 1930 (I0 = X MCS), 1962 (I0 = IX MCS) and 1980 (I0 = X MCS), all with epicenters in the Campania and Basilicata regions. The last one is still deeply engraved in the collective memory, having led to the deaths of nearly 3000 individuals and resulted in the near-total destruction of some Apennine villages. Moreover, the city of Naples has also been hit by ancient historical earthquakes that originated in the Campanian volcanic districts of Campi Flegrei, Vesuvio and Ischia, with intensities up to VII&ndash, VIII MCS (highest in the Vesuvian area). Based on the intensity and frequency of its past earthquakes, the city of Naples is currently classified in the second seismic category, meaning that it is characterized by &ldquo, seismicity of medium energy&rdquo, In this paper, we determine the level of damage suffered by Naples and its monuments as a result of the strongest earthquakes that have hit the city throughout history, highlighting its repetitiveness in some areas. To this aim, we reconstructed the seismic history of some of the most representative urban monuments, using documentary and historical sources data related to the effects of strong earthquakes of the Southern Apennines on the city of Naples. The ultimate purpose of this study is to perform a seismic macro-zoning of the ancient center of city and reduce seismic risk. Our contribution represents an original elaboration on the existing literature by creating a damage-density map of the strongest earthquakes and highlighting, for the first time, the areas of the city of Naples that are most vulnerable to strong earthquakes in the future. These data could be of fundamental importance to the construction of detailed maps of seismic microzones. Our study contributes to the mitigation of seismic risk in the city of Naples, and provides useful advice that can be used to protect the historical heritage of Naples, whose historical center is a UNESCO World Heritage site.

The earthquake environmental effects (EEEs) around the epicentral area of the Pohang earthquake (Mw-5.4) that occurred on 15 November 2017 have been collected and classified using the Environmental Seismic Intensity Scale (ESI-07 scale) proposed by the International Union for Quaternary Research (INQUA) focus group. The shallow-focus 15 November Pohang earthquake did not produce any surface rupture, but caused extensive secondary environmental effects and damage to life-line structures. This earthquake was one of the most damaging earthquakes during the instrumental seismic era of the Korean Peninsula. The EEEs included extensive liquefaction, ground cracks, ground settlement, localized rockfall, and variation of the water table. The main objective of this paper was to carry forward a comparative assessment of the Pohang earthquake&rsquo, s intensity based on traditional macroseismic scales and the ESI-07 scale. With that objective, this study will also make a substantial contribution to any future revision of the ESI-07 scale, which mostly comprises case studies from Europe and South America. The comparison of the ESI-07 scale with traditional intensity scales similar to the intensity scale used by the Korean Meteorological Administration for the epicentral areas showed 1&ndash, 2-degree differences in intensity. Moreover, the ESI scale provided a clearer picture of the intensity around the epicentral area, which is mostly agricultural land with a lack of urban units or buildings. This study urges the integration of the traditional and ESI-07 scale for such small magnitude earthquakes in the Korean Peninsula as well as around the world in future. This will predict seismic intensity more precisely and hence provide a more-effective seismic hazard estimation, particularly in areas of low seismic activity. The present study will also provide a useful and reliable tool for the seismic hazard assessment of similar earthquakes around the study area and land-use planning at a local scale considering the secondary effects.

On 26th January 2001, an earthquake of magnitude Mw 7.7 occurred near Bhuj, in northwestern India, resulting in severe environmental effects. No unequivocal primary surface rupture was observed for the earthquake, but it caused widespread liquefaction and lateral spreading in the Rann of Kachchh and Little Rann. After the earthquake, several researchers collected field evidence of secondary surface rupture, rockfall, dry craters, and surface manifestations of liquefaction, including the formation of mud volcanoes and lateral spreads, in the meizoseismal area. Analysis of pre- and post-earthquake satellite images suggests that several “dry” streams in the Rann of Kachchh began to flow due to extensive liquefaction induced by the earthquake. In this present study, the macroseismic intensity of the Bhuj earthquake is evaluated by considering these environmental effects and applying the ESI-07 intensity scale to the affected area. As an outcome, the epicentral intensity of the 2001 Bhuj earthquake was determined to be XI. According to historical records and seismic catalogs, 16th June 1819 Allah Bund earthquake caused prominent surface rupture which was not so clear in the case of 2001 Bhuj earthquake, but the secondary effects were similar for both earthquakes. Considering the environmental effects caused by the 1819 Allah Bund earthquake, an intensity of XI was estimated for the epicentral area. For both earthquakes, the ESI scale yields a significant difference of one to two degrees with the traditional intensity scales. The 2001 Bhuj earthquake and 1819 Allah Bund earthquake shows similar ESI-07 intensity of XI despite of different epicentral locations. This implies the reliability of ESI-07 scale application for different earthquakes of similar dimensions in the same geological setting. This study contributes to the application of ESI-07 scale for Indian earthquakes, especially reverse faulting events, and to the future improvement of the ESI scale with emphasis on its applicability to historical earthquakes on the Indian subcontinent. Also, this study may help in future land use planning in the meizoseismal area of 1919 Allah Bund and 2001 Bhuj earthquakes.

The aim of this study is to describe the modifications of the built environment that have occurred in 36 years following the Irpinia-Basilicata, 1980 earthquake. In particular, especially in the villages of the epicentral area, changes in the urban and territorial setting have been examined, as well as the consequences of ground effects that have influenced the choices of reconstruction, both in situ, and far from the original historical centers. The November 23, 1980 Irpinia-Basilicata earthquake (Mw = 6.9; Io = X MCS; Io = X ESI-07), killing 3000 people, hit 800 localities over a large area of Southern Italy; 75,000 houses totally collapsed and 275,000 were badly damaged. The earthquake induced primary and secondary environmental effects, over all slope movements. The total amount of surface faulting was 40 km in length with the maximum displacement of 100 cm; the total area affected by slope movements was estimated to be about 7400 km2, with 200 landslides classified. One of the largest landslides damaged Calitri village, in Avellino province. We have examined, as case histories, the reconstruction of Calitri and San Mango sul Calore villages, that were affected by severe landslides and were rebuilt in situ; we have also studied Conza della Campania that was reconstructed far from the original location. In the so-called Anthropocene age, the role of technical experts both in the built environment and in the social and ethical context is extremely important, for rebuilding the villages destroyed by earthquakes, especially in respect of the people resilience.

The 23 July 1930 earthquake (MS=6.7) in the Southern Apennines (Italy) was a catastrophic event that produced many effects such as surface faulting, fractures, landslides, settlements, hydrological changes, variations in chemical/physical activity related to the volcanic and/or thermal zones and also acoustic and optical phenomena. It is the first great earthquake of the twentieth century that was studied, thanks to the hydrological monitoring network of the Italian Hydrographic Survey (IHS) set up from 1925 to 1929. For this earthquake we analysed the initial IHS hydrometric and pluviometric data, looking for significant anomalies in springs, water wells and mountain streams. Hydrological data relative to rivers, springs and water wells indicate that some changes can be correlated with the earthquake: a post-seismic excess discharge in some streams, pre- and co-seismic decreases in stream flows and water levels in wells, pre- and post-seismic increases in discharges. The pre- and co-seismic stresses and the tectonic deformations were studied in order to find a possible model of interaction between stress state and hydrological variations. The anomalies found in this work can be considered "rebound anomalies", which are the most common precursor reported by many authors and related to increases in porosity and permeability caused by the fracturing that precedes an earthquake. An estimation of the total excess discharge (0.035 km3) caused by the MS=6.7 Irpinia earthquake is consistent with the excess discharge of about 0.01 km3 determined for the Mw=6.9 Loma Prieta earthquake.

Guatemala is one of the most seismically active countries of Central America. It has suffered several dramatic earthquakes during the last century, the most destructive of which was the event associated with the Motagua fault, occurred on 4, February 1976, that caused 23,000 deaths, and 77,200 injuries. Noteworthy were also the coseismic geological effects, either directly linked to the earthquake source, such as a remarkable displacement along a 230 km long strike-slip fault, or caused by the ground shaking, such as 50,000 landslides, numerous liquefaction phenomena, ground cracks and ground deformation over an area of about 18,000 km2. In spite of this, the estimated intensity was relatively low (Imax = IX MM, only in few localities). For this reason, in order to achieve a better definition of seismic hazard, we have conducted a re-evaluation of the 1976 earthquake taking into account the environmental effects that have contributed substantially to the dramatic level of recorded impact, both in terms of loss of human life and damage affecting housing and infrastructures. The analysis of primary and secondary effects has permitted a better evaluation of seismic intensity in 24 localities that were hit by the earthquake and allowed for establishing a new epicentral Intensity, characterized by XI ESI. The recalculated seismic intensity is consequently two degrees higher than previous estimates and definitely more consistent with the scenario of the actual damage caused by the earthquake.

A major hydrogeological problem affecting the Amalfi coast (Southern Italy) involves slope-related processes mainly due to flash floods typically characterized by landslides of debris flow type. These processes are generated on slopes and interact heavily with river dynamics, mobilizing huge quantities of material which are then carried by the water course. In the area of Cava de’ Tirreni, phenomena of torrential spate have occurred regularly in historical times due to the presence of volcaniclastic deposits and soils on slopes which are very prone to being mobilized and washed away during rainfall events. For the historical reconstruction of the 11–12th November 1773 flood event, over one hundred archival sources contemporary to the event were examined, as well as many bibliographic sources. The conclusions of our research were compared and integrated with results from updated literature.

Moderate to strong crustal earthquakes are generally accompanied by a distinctive pattern of coseismic geological phenomena, ranging from surface faulting to ground cracks, landslides, liquefaction/compaction, which leave a permanent mark in the landscape. Therefore, the repetition of surface faulting earthquakes over a geologic time interval determines a characteristic morphology closely related to seismic potential. To support this statement, the areal distribution and dimensions of effects of recent historical earthquakes in the Southern Apennines are being investigated in detail. This paper presents results concerning the 26 July 1805 earthquake in the Molise region, (I =X MCS, M = 6.8), and the 23 November 1980 earthquake in the Campania and Basilicata regions (I =XM SK,Ms = 6.9). Landslide data are also compared with two other historical earthquakes in the same region with similar macroseismic intensity. The number of significant effects (either ground deformation or hydrological anomalies) versus their minimum distance from the causative fault have been statistically analyzed, finding characteristic relationships. In particular, the decay of the number of landslides with distance from fault follows an exponential law, whereas it shows almost a rectilin- ear trend for liquefaction and hydrological anomalies. Most effects fall within the macroseismic area, landslides within intensity V to VI, liquefaction effects within VI and hydrological anomalies within IV MCS/MSK, hence at much larger distances. A possible correlation between maximum distance of effects and length of the reactivated fault zone is also noted. Maximum distances fit the envelope curves for Intensity and Magnitude based on worldwide data. These results suggest that a careful examination of coseismic geological effects can be important for a proper estimation of earthquake parameters and vulnerability of the natural environment for seismic hazard evaluation purposes.

The study of hydrological variations in the watersheds of seismic areas can be useful in order to acquire a new knowledge of the mechanisms by which earthquakes can produce hydrological anomalies. Italy has the availability of many long historical series both of hydrological parameters and of seismological data, and is an ideal laboratory to verify the validity of theoretical models proposed by various authors. In this work we analyse the hydrological anomalies associated with some of the big earthquakes that occurred in the last century in the southern Apennines: 1930, 1980 and 1984. For these earthquakes we analysed hydrometric and pluviometric data looking for significant anomalies in springs, water wells and mountain streams. The influence of rainfalls on the normal flows of rivers, springs and wells has been ascertained. Also, the earthquake of 1805, for which a lot of hydrological perturbations have been reported, is considered in order to point out effects imputable to this earthquake that can be similar to the effects of the other big earthquakes. The considered seismic events exhibit different modes of energy release, different focal mechanisms and different propagation of effects on the invested areas. Furthermore, even if their epicentres were not localised in contiguous seismogenetic areas, it seems that the hydrological effects imputable to them took place in the same areas. Such phenomena have been compared with macroseismic fields and transformed in parameters, in order to derive empirical relationships between the dimensions of the event and the characteristics of the hydrological variations. The results of this work point to a close dependence among hydrological anomalies, regional structures and fault mechanisms, and indicate that many clear anomalies have been forerunners of earthquakes. In 1993, the Naples Bureau of the Hydrographic National Service started the continuous monitoring of hydrologic parameters by a network of automatic stations and transmission in real time; presently 7 acquifers are under control in which also pH, T , salinity, electrical conductivity, dissolved oxygen are measured. We envisage to increase the number of monitoring sites and controlled parameters.

This paper both describes and discusses landslides and other ground effects induced by the September–October 1997 seismic sequence, which struck the Umbria and Marche regions (Central Italy). Three main events occurred on 26 September at 00:33 and 09:40 GMT, and 14 October with magnitude M w equal to 5.8, 6.0 and 5.4, respectively; furthermore hundreds of minor but significant events were also recorded. The authors examined an area of some 700 km 2 around the epicentre (Colfiorito). Primary and secondary effects were observed, including surface faulting phenomena, landslides, ground fractures, compaction and various hydrological phenomena. Surface evidence of faulting reactivation was found along the well-known capable faults, to a total length of ca. 30 km. Landslides, which were the most recurrent among the phenomena induced, consisted mainly of rock falls and subordinately of rotational and translational slides, which were generally mobilised by the inertia forces during the seismic motion. The percentage of reactivated old landslides decreased as the distance from the epicentral zone increased; a similar decrease had been observed for the 1980 Irpinia earthquake (Southern Italy). The ground fracture distribution was consistent with the regional structural setting and the general pattern of macroseismic field. Numerous episodes of hydrological changes were observed within the most severely damaged area. All this evidence confirms the relevance of the study of ground surface effects for achieving a more complete evaluation of seismic hazard.

The September–October 1997 seismic sequence in the Umbria–Marche regions of Central Italy (main shocks on September 26, Mw 5.7 and 6.0, and on October 14, Mw 5.6) left significant ground effects, which were mainly concentrated in the Colfiorito intermountain basin. These effects included surface faulting, ground cracks and settlements, rock falls, slides, hydrological and gas anomalies. The distribution and size of ground effects has proved useful for (1) defining the epicentral area and the location of the causative fault; (2) complementing the intensity pattern from damage distribution (this can be very useful in poorly inhabited zones); (3) integrating or testing the intensity assessment of many historical events, in order to obtain a better evaluation of the magnitude from intensity data. Of special interest was the observation of surface ruptures generated along segments of a system of normal faults already mapped as capable, with end-to-end lengths of 12 km and maximum displacements of 8 cm. Many pieces of evidence confirm that coseismic slip was not a secondary, gravity-induced, phenomenon, but had a tectonic origin. Detailed descriptions of surface faulting for moderate earthquakes are not common, being easily missed or misinterpreted; however, in this paper we emphasize that surface faulting due to the 1997 event can be used to infer the threshold magnitude for surface faulting in Central Apennines, allowing to calibrate palaeoearthquake size from fault offsets as seen in trench investigations.

A reconstruction of historical floods occurred along the Amalfi coast, during the last five centuries is presented. The analysis of historical sources allowed to achieve a chronological reconstruction of more than 100 floods, four of which classified as catastrophic events. In this task, the level of information was decisive to carry out space-time identification, estimate the affected area and define the type of damage to the structures, and the environment (e.g. mud flow, debris flow, rock falls, shoreline progradation, fan deltas), which may be relevant for the recognition of similar events within the geologic record. The magnitude of the events was finally estimated, taking into account the size of the areas affected by flooding as well as the type of effects induced on the urban and physical environment and the recurrence intervals. © Springer-Verlag Berlin Heidelberg 2013.

Analysis of distribution of landslides (rock falls and coherent slides), induced by 12 moderate to strong earthquakes occurred in the last three centuries in Central-Southern Apennines, has permitted to investigate the relationship of their maximum distance versus magnitude and ESI epicentral intensity. For coherent slides, the correlation of magnitude or ESI intensity versus distance is fairly good and consistent with global datasets. Instead, rock falls show a less evident correlation with distance. We stress here the usefulness of such relationships to define the expected scenario of earthquake-induced landslides. However, the data base needs to be improved and enlarged to allow more robust estimates. © Springer-Verlag Berlin Heidelberg 2013.

On 9 September 1998, at 13:28 local time (11:28 UTC), a moderate earthquake of Mw = 5.6 struck the Southern Apennines at the northwest margin of the Pollino Massif (the highest mountain range of the region, reaching elevations above 2,000 m a.s.l.; Figures 1 and 2). The macroseismic epicenter is located about 3 km southeast of Lauria, with a maximum intensity of VIII on the MCS scale (or MM or MSK; see below for a correlation among macroseismic scales); thus we refer to this event as the Lauria earthquake. Historical towns—such as Lagonegro, Lauria, and Castelluccio—suffered significant damage, in particular that of Rivello, which is a remarkable local artistic site. Several ground effects followed the shock, and a rockfall on the road between Cersuta and Acquafredda (site 9a in Figure 3) claimed one life. A moderate magnitude event, the Lauria earthquake, together with the 5 May 1990 Potenza earthquake ( Ms = 5.4), was the largest earthquake in southern Italy since the destructive 23 November 1980 Irpinia earthquake (Alessio et al., 1995, cum bib.; Table 1 and Figure 2A). The day after the shock we initiated a reconnaissance survey of the epicentral area in order to record the geological and environmental changes induced by the earthquake. Among many other effects, we observed the rejuvenation of a bedrock fault scarp. In this paper we focus on this evidence of tectonic surface rupture because it has significant implications for the seismic hazard assessment both in (a) this sector of the Apennines and (b) other parts of the world. 1. This is the first modern observation of earthquake surface rupture in the apparently “aseismic” Pollino region. Figure 2 shows that according to the historical seismic catalogs only a few moderate to small local earthquakes (I ≤ VIII MCS) affected this area, in …

On Oct. 4th, 1983 the area of Phlegraean Fields, near Naples (Southern Italy) was shaked by an earthquake of magnitude (M L) 4.0 that caused some damage in the town of Pozzuoli and its surroundings. This seismic event was the largest one recorded during the recent (1982–84) inflation episode occurred in the Phlegraean volcanic area, and a detailed macroseismic reconstruction of the event was carried out. Failing macroseismic data on other earthquakes occurred in Phlegraean Fields, the attenuation law of the intensity as a function of the distance as obtained for the Oct. 4th earthquake was compared with those obtained for other volcanic areas in central Italy —i.e., Tolfa, Monte Amiata — in order to check the reliability of the results obtained for Phlegraean Fields. The Blake's model of the earthquake of Oct. 4th, 1983 does not agree with the experimental data because isoseismals contain areas larger than those shown by the model. This result has been interpreted as an effect of energy focusing due to a reflecting layer 6–8 km deep.

The aim of this study was to provide a contribution to seismic hazard assessment of the Salento Peninsula (Apulia, southern Italy). It is well known that this area was struck by the February 20, 1743, earthquake (I 0 = IX and M w = 7.1), the strongest seismic event of Salento, that caused the most severe damage in the towns of Nardo (Lecce) and Francavilla Fontana (Brindisi), in the Ionian Islands (Greece) and in the western coast of Albania. It was also widely felt in the western coast of Greece, in Malta Islands, in southern Italy and in some localities of central and northern Italy. Moreover, the area of the Salento Peninsula has also been hit by several low-energy and a few high-energy earthquakes over the last centuries; the instrumental recent seismicity is mainly concentrated in the western sector of the peninsula and in the Otranto Channel. The Salento area has also experienced destructive seismicity of neighboring regions in Italy (the Gargano Promontory in northern Apulia, the Southern Apennines chain, the Calabrian Arc) and in the Balkan Peninsula (Greece and Albania). Accordingly, a critical analysis of several documentary and historical sources, as well as of the geologic–geomorphologic ground effects due to the strong 1743 Salento earthquake, has been carried out by the authors in this paper; the final purpose has been to re-evaluate the 1743 MCS macroseismic intensities and to provide a list of newly classified localities according to the ESI-07 scale on the base of recognized Earthquake Environmental Effects. The result is a quite different damage scenario due to this earthquake that could raise the seismic potential currently recognized for the Salento area, and consequently upgrade the seismic hazard classification of the Salento. Indeed it is important to remind that currently, despite the intense earthquake activity recorded not only in the Otranto Channel, but especially in Greece and Albania, this area is classified in the least dangerous category of the Seismic Classification of the Italian territory (IV category).

In this paper some extreme flooding events occurred in the Campania Region, particularly in the Salerno province since the XVI century, and in the Somma-Vesuvius volcanic complex since the beginning of the XX century, have been analyzed. Through a multidisciplinary approach based on detailed bibliographic and archival documents investigation, besides geologic-geomorphologic analyses, in GIS environment, the landslide distribution and frequency in the last centuries, inside these two areas, has been examined, jointly with the urbanization evolution for the Vesuvius area. In particular, seven flood events, the 1581, 1588, 1773, 1899, 1910, 1924 and the 1954 floods occurred in the Salerno province, have been studied in detail; while the alluvial phenomena occurred in the Somma-Vesuvius district, repeatedly affected by disastrous flood events, and occurred from 1906 to 2011, have been reported. Although this study is not exhaustive, it aims to contribute, illustrating a methodology for data searching and analyzing, to a correct assessment and reduction of hydrogeological risk in the Campania region.